The curable resin composition containing a polymer having a hydrolyzable silyl group undergoes hydrolysis and condensation reaction due to moisture or the like in the air or on adherends so as to yield rubber-like cured products. The cured products have flexibility even at a relatively low temperature, and thus are widely used for coatings, adhesives, sealants, etc.
In order to accelerate the above reaction, a curing catalyst is usually used. The curing catalyst is required to have a property of being kept stable without gelation or increase in viscosity of the curable resin composition in a sealed condition shielded from humidity. On the other hand, it is required to cause the curable resin composition to rapidly react to cure when coated on an adherend. As conventionally-known curing catalysts, organic tin catalysts such as dibutyltin bis(acetylacetonate) and dibutyltin laurate have been widely used. However, toxicity of these organic tin compounds has been recently noticed, and various other curing catalyst have been investigated. For example, other metal catalysts than organic tin compounds (Patent Documents 1 and 2), acid catalysts (Patent Documents 3 and 4), amine-based catalysts (Patent Document 5), and boron trifluoride-based catalysts (Patent Document 6) have been proposed. Acid catalysts that are blocked with amine (Patent Documents 7 and 8) have also been proposed in order to improve storage stability of curable resin compositions of one-pack type. A combination of an amidine-containing compound with a sulfonyl group-containing compound (Patent Document 9) and a combination of a fluoride and a protonic acid (Patent Document 10) have also been proposed.